5 WHY – solve the problem in the place where it was created

5 WHY Analysis – introduction


The process of continuous improvement, through the use of Lean philosophy, gives us many opportunities and tools to solve problems. However, to choose the right course of action that will help us to implement effective corrective actions, it is first necessary to identify the CAUSE OF SOURCE arising from the problem.


This is a very important element before proceeding to the “repair process”. Extinguishing a fire and solving a “hot” problem, without identifying the main cause of its occurrence, may result in the topic returning again. And we can even be sure of that!


What tools can we use to solve the problem?

  1. Ishikawa Cause and Effect Chart (so-called fishbone diagram)

  2. Experiment Planning (Design of Experiments, DoE)

  3. Analysis of the history of changes (what and when was changed and when the problem was detected)

  4. 5 WHY analysis

  5. Analysis of statistical data (Cpk, Pareto, Anova, …)

  6. Brainstorm

  7. And other…


The method on which I will focus this time is called the 5 Why analysis. Often you can also find the version of Analysis 5 Why, 1 How.


5 Why analysis is extremely simple and fast in practical use, therefore it is recommended to carry out the problem detection. A short training course is enough for anyone who participates in the analysis of 5 Why, and has never dealt with it, understood what it is.


First things first…


Main aspects of the 5 Why analysis


Before starting the analysis, focus on two issues, namely:


1. Why the problem arose?

What are the reasons for the problem? If you are talking about a production company, why was the defect produced? In the service industry, for example, why was the mistake made?


2. Why did not we notice the reason for the problem earlier?


We already know that there was a problem, where it was detected, how big is the problem, but why have not we seen before that something in the process is wrong? That something deviates from the norm, from the standard? Or maybe there is no standard, or is it out of date ??


This is another issue that needs to be clarified. More specifically, one has to answer the question: Why did our current system, control method or process supervision not detect the problem immediately after its creation?


Before you start the 5 Why analysis


Collect information about the problem

The more information you collect at the beginning, the more likely you are to get to the actual source of the problem.

It is important to analyze:

– What actually happened?

– When did this happen or when it was detected?

– Who detected the problem?

– What is the scale of the problem?

– If we are talking about a production company, how many deficiencies and defects have arisen?

– Does the detected problem pose any threat to the client, user or enterprise? If so, which ones?

– Has the problem appeared for the first time? Has there been a similar event in the past?


Name team – working group

The next step is to gather a team, a group of people who knows the most about the process and which can help to determine the cause of the problem.

There is no requirement as to how many people should be included in such a working group. It is important, however, that employees associated with a given process are among them. They know the details and all the nuances of these operations and will be able to identify what went wrong, at what stage the error occurred.


Describe the problem


Information about the problem is already collected, a working group is set up, so it’s time to describe exactly what happened and start the right analysis. 5 Why.

This is a very important element, not only in the analysis of 5 Why, but in any method of solving problems.

Allows you to concentrate on the heart of the matter, clearly defines the facts. If it happens that the discussion during the analysis starts to go in a different direction, the moderator can easily return to the right topic.


Time for the right analysis, so lets get start!


5 Why analysis is consistently asking the question: Why … (the content of the problem)?

It is assumed that the 5-fold task of the question “why … (the content of the answer from the previous question)?” Should lead us to the root cause of the problem.

In practice, it may be enough to ask, for example, 4 questions “Why?” Or it will be necessary to further explore the topic. It all depends on the complexity of the problem and possible causes.


Tip # 1: If after the 5th question you still will not be closer to solving the problem, you will need to choose another method. The problem we are analyzing is more complicated and requires more precise methods of analysis.


Tip # 2: Use the “no blame culture” approach, i.e. do not assume that the main cause of the problem is a mistake, an oversight of the employee. 99% of the causes of problems lie on the side of the process that does not protect the user from making a mistake.




Problem content: There is no “X” hole on detail No. 21.

1 Why: Why is the X hole missing on detail # 21?

A: The drilling operation was omitted.

2 Why: Why did you omit the drilling operation?

A: Details before and after the drilling operation are next to each other.

3 Why: Why are the details before and after drilling operations lying side by side?

A: No specific space designated for details before and after the drilling operation.

4 Why: Why is there no specific place for details before and after the drilling operation?

A: The process technologist did not specify the rules for identifying and storing parts before and after the drilling process.


5 Why: Why did the process technologist not specify the rules for identifying and storing parts before and after the drilling process?

A: There are no clear rules and guidelines for labeling products before and after the process throughout the company.


The root cause of the problem: Lack of clear rules and guidelines for marking products before and after the process throughout the company.


Now it remains to determine what needs to be done so that the problem does not happen again in the future. If there are no guidelines – you have to develop them, then implement them and train all those who are involved in the process.

It is also important to appoint persons responsible for the implementation of the changes and the deadline for when the tasks will be carried out.

1 How: What should I do to make the products before and after the process clearly marked?


Possible answer: Mark in green and describe the place of placing on the details after the process, and the color orange – before the process. If the details do not meet the quality requirements, they should be put back in place marked in red.

Apply the rule to all processes.

End of analysis. I do not think it was difficult, right?


In the Infographics tab (only polish version), downloadable materials for the analysis of 5 Why are available.

I encourage you to familiarize yourself with them and other methods and tools of continuous improvement.



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